Hi everyone

I am trying to design a BMS and currently working on the external balancing circuit. I found that the balance current is different than the load discharge current but I want to understand how to determine the balance current. The balance control current is found in the datasheet.
Thank you

 

is there a question?

 

Yes how to determine the balance current

 

You need to know the balance resistor value, the Rds of the mosfet the voltage of the battery and the gate voltage.

To simplify figure out the resistance of the circuit then solve for current based on the battery voltage using ohms law

 

Yes I want to select these components based on the balance current, but what value is best for the balance current?

 

Ah that’s a tricky one. Too many variables. It really depends on whether this is done while charging or whether it’s actively balancing all the time. Suggest you research on how this is done and what your controller does. I’m not familiar with that chip. Usually it’s a low current so the battery does not get too hot but high enough that it balances in a reasonable amount of time.